How would that affect the plans to renovate Tower 1 and 4 of the 5 approach interlockings? Those projects, along with the expanded layovers, are just as vital to SSX terminal capacity needs as the 7 extra tracks. Even then SS will triple in size under the current plan (200,000sf + expansion 410,000 sf), I see stacking the platforms + concourse as a more expensive objective than eating up USPS. Gobble up USPS or die.There is nothing (but cost) to prevent you from going UNDER the current tracks for another level. The Bus Station had to straddle the tracks, so you know where those footers are.
Basically create a near duplicate platform "under". Complex construction -- sure. But make it as a threat to the USPS (we don't really need you!). Many stations in Europe are dual level like that.